Field of the Invention
The present invention relates to a geopolymer activator composition and geopolymer binder, paste and concrete compositions comprising the geopolymer activator composition. The invention further relates to a method for preparing a geopolymer composition on the basis of the geopolymer activator composition.
Description of Related Art
Geopolymer concrete production, i.e. the making of artificial stone, is a promising and potential sustainable technique for the production of the new construction materials. Geopolymer compositions can partially replace the need of currently used conventional construction materials, e.g. cement mortar, cement concrete and asphalt. A replacement of the conventional construction materials has environmental and sustainable advantages, because waste minerals can be used as secondary raw mineral in the production of geopolymers.
Geopolymers are typically formed by reacting an alkaline liquid with a geological based source material. The reaction product from this material can be used to bind aggregate to form concrete. The geological based source materials, i.e. minerals, preferably contain a high content of aluminum, silicon, calcium and iron. Due to high alkalinity of the mixture the solid minerals dissolve to form aluminum, silicon, calcium and iron monomers. The monomers will start to form a polymerized network when contacted with a geopolymer activator composition and, combined with the aggregate, a covalently bonded network grows over time resulting in a concrete that may be more stable compared to cement, which is based on a crystalline bonded network.
The production of geopolymer compositions is costly and typically has a bad workability. An important drawback is the need for elevated temperatures to initiate the geopolymerization process, which is important to increase the compressive strength of the geopolymer material. Furthermore, another drawback is the need for excessive amounts of alkaline components.
The present invention aims to provide a geopolymer concrete or paste composition that can be cured at ambient temperature and simultaneously have sufficient strength and are less costly to prepare compared to the production methods known in the art.